Tissue extraction devices and methods

ABSTRACT

A tissue resection device comprises inner and outer coaxial sleeves. The outer sleeve has a cutting window formed therein, and the inner sleeve has a distal cutting end that can be reciprocated past the cutting window. The sleeves comprise electrodes to provide electrosurgical cutting, and an edge portion of the window includes a dielectric material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/205,178, filed Jul. 8, 2016, now U.S. Pat. No. 9,743,979, which is acontinuation of U.S. application Ser. No. 13/599,928, filed Aug. 30,2012, now U.S. Pat. No. 9,439,720, which claims priority to U.S.Provisional Application No. 61/530,314, filed Sep. 1, 2011; U.S.Provisional Application No. 61/534,256, filed Sep. 13, 2011; U.S.Provisional Application No. 61/538,588, filed Sep. 23, 2011; U.S.Provisional Application No. 61/541,803, filed Sep. 30, 2011; and U.S.Provisional Application No. 61/556,646, filed Nov. 7, 2011; the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates systems and methods for the cutting andextraction of uterine fibroid tissue, polyps and other abnormal uterinetissue.

BACKGROUND OF THE INVENTION

Uterine fibroids are non-cancerous tumors that develop in the wall ofuterus. Such fibroids occur in a large percentage of the femalepopulation, with some studies indicating up to 40 percent of all womenhave fibroids. Uterine fibroids can grow over time to be severalcentimeters in diameter and symptoms can include menorrhagia,reproductive dysfunction, pelvic pressure and pain.

One current treatment of fibroids is hysteroscopic resection ormyomectomy which involves transcervical access to the uterus with ahysteroscope together with insertion of a cutting instrument through aworking channel in the hysteroscope. The cutting instrument may be amechanical tissue cutter or an electrosurgical resection device such asa cutting loop. Mechanical cutting devices are disclosed in U.S. Pat.Nos. 7,226,459; 6,032,673 and 5,730,752 and U.S. Published Patent Appl.2009/0270898. An electrosurgical cutting device is disclosed in U.S.Pat. No. 5,906,615.

Electrosurgical cutting devices having inner and outer tubes with acutting window in the outer sleeve are described in commonly ownedapplication Ser. Nos. 13/531,309; 13/277,913; 13/442,686; and13/534,980, the full disclosures of which are incorporated herein byreference.

While hysteroscopic resection can be effective in removing uterinefibroids, many commercially available instrument are too large indiameter and thus require anesthesia in an operating room environment.Conventional resectoscopes require cervical dilation to about 9 mm. Whatis needed is a system that can effectively cut and remove fibroid tissuethrough a small diameter hysteroscope.

SUMMARY OF THE INVENTION

The present invention provides improvement electrosurgical cuttingdevices comprising an outer tube and an inner tube reciprocatablydisposed in a central lumen or passage of the outer tube. The tubes areeach formed from or include electrically conductive materials so thatthey act as the electrodes of the electrosurgical cutting device whenconnected to opposite poles of an electrosurgical power supply.

In accordance with the present invention, a dielectric material isdisposed over or incorporated into a structure circumscribing thecutting window or the outer tube. The dimensions and geometry of thedielectric structure are chosen to optimize plasma generation about acutting end or electrode at a distal end of the inner electrode as theinner electrode is advanced (with radiofrequency energy being applied)past the cutting window with tissue invaginated within the window.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an assembly including a hysteroscope and atissue-cutting device corresponding to the invention that is insertedthrough the working channel of the hysteroscope.

FIG. 2 is a schematic perspective view of a fluid management system usedfor distending the uterus and for assisting in electrosurgical tissuecutting and extraction.

FIG. 3 is a cross-sectional view of the shaft of the hysteroscope ofFIG. 1 showing various channels therein.

FIG. 4 is a schematic side view of the working end of theelectrosurgical tissue-cutting device of FIG. 1 showing an outer sleeveand a reciprocating inner sleeve and an electrode arrangement.

FIG. 5 is a schematic perspective view of the working end of the innersleeve of FIG. 4 showing its electrode edge.

FIG. 6A is a schematic cut-away view of a portion of outer sleeve, innerRF cutting sleeve and a tissue-receiving window of the outer sleeve.

FIG. 6B is a schematic view of a distal end portion another embodimentof inner RF cutting sleeve.

FIG. 7A is a cross sectional view of the inner RF cutting sleeve of FIG.6B taken along line 7A-7A of FIG. 6B.

FIG. 7B is another cross sectional view of the inner RF cutting sleeveof FIG. 6B taken along line 7B-7B of FIG. 6B.

FIG. 8 is a schematic view of a distal end portion of another embodimentof inner RF cutting sleeve.

FIG. 9A is a cross sectional view of the RF cutting sleeve of FIG. 8taken along line 9A-9A of FIG. 8.

FIG. 9B is a cross sectional view of the RF cutting sleeve of FIG. 8taken along line 9B-9B of FIG. 8.

FIG. 10A is a perspective view of the working end of the tissue-cuttingdevice of FIG. 1 with the reciprocating RF cutting sleeve in anon-extended position.

FIG. 10B is a perspective view of the tissue-cutting device of FIG. 1with the reciprocating RF cutting sleeve in a partially extendedposition.

FIG. 10C is a perspective view of the tissue-cutting device of FIG. 1with the reciprocating RF cutting sleeve in a fully extended positionacross the tissue-receiving window.

FIG. 11A is a sectional view of the working end of the tissue-cuttingdevice of FIG. 10A with the reciprocating RF cutting sleeve in anon-extended position.

FIG. 11B is a sectional view of the working end of FIG. 10B with thereciprocating RF cutting sleeve in a partially extended position.

FIG. 11C is a sectional view of the working end of FIG. 10C with thereciprocating RF cutting sleeve in a fully extended position.

FIG. 12A is an enlarged sectional view of the working end oftissue-cutting device of FIG. 11B with the reciprocating RF cuttingsleeve in a partially extended position showing the RF field in a firstRF mode and plasma cutting of tissue.

FIG. 12B is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF cutting sleeve almost fully extended andshowing the RF fields switching to a second RF mode from a first RF modeshown in FIG. 12.

FIG. 12C is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF cutting sleeve again almost fully extended andshowing the explosive vaporization of a captured liquid volume to expelcut tissue in the proximal direction.

FIG. 13 is an enlarged perspective view of a portion of the working endof FIG. 12C showing an interior chamber and a fluted projecting element.

FIG. 14 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element.

FIG. 15 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element configured toexplosively vaporize the captured liquid volume.

FIG. 16A is a view of the working end of an outer sleeve with windowhaving edge features prepared for coupling with a dielectric material.

FIG. 16B is a view of the working end of the outer sleeve of FIG. 16Aafter coupling with the dielectric edge.

FIG. 16C is another view of the working end of the outer sleeve of FIG.16A after coupling an additional dielectric inner sleeve material.

FIG. 17 is an enlarged view of a portion of a working end as in FIGS.16A-16C showing dielectric m FIG. 16A is a view of the working end of anouter sleeve with window having edge features prepared for coupling witha dielectric material.

FIG. 18 is a view of another working end of an outer sleeve differentedge features prepared for coupling with a dielectric material.

FIG. 19 is a view of another variation of working end similar to that ofFIGS. 16A-16C showing an alternative electrode arrangement.

DETAILED DESCRIPTION

FIG. 1 illustrates an assembly that comprises an endoscope 50 used forhysteroscopy together with a tissue-extraction device 100 extendingthrough a working channel 102 of the endoscope. The endoscope orhysteroscope 50 has a handle 104 coupled to an elongated shaft 105having a diameter of 5 mm to 7 mm. The working channel 102 therein maybe round, D-shaped or any other suitable shape. The endoscope shaft 105is further configured with an optics channel 106 and one or more fluidinflow/outflow channels 108 a, 108 b (FIG. 3) that communicate withvalve-connectors 110 a, 110 b configured for coupling to a fluid inflowsource 120 thereto, or optionally a negative pressure source 125 (FIGS.1-2). The fluid inflow source 120 is a component of a fluid managementsystem 126 as is known in the art (FIG. 2) which comprises a fluidcontainer 128 and pump mechanism 130 which pumps fluid through thehysteroscope 50 into the uterine cavity. As can be seen in FIG. 2, thefluid management system 126 further includes the negative pressuresource 125 (which can comprise an operating room wall suction source)coupled to the tissue-cutting device 100. The handle 104 of theendoscope includes the angled extension portion 132 with optics to whicha videoscopic camera 135 can be operatively coupled. A light source 136also is coupled to light coupling 138 on the handle of the hysteroscope50. The working channel 102 of the hysteroscope is configured forinsertion and manipulation of the tissue-cutting and extracting device100, for example to treat and remove fibroid tissue. In one embodiment,the hysteroscope shaft 105 has an axial length of 21 cm, and cancomprise a 0° scope, or 15° to 30° scope.

Still referring to FIG. 1, the tissue-cutting device 100 has a highlyelongated shaft assembly 140 configured to extend through the workingchannel 102 in the hysteroscope. A handle 142 of the tissue-cuttingdevice 100 is adapted for manipulating the electrosurgical working end145 of the device. In use, the handle 142 can be manipulated bothrotationally and axially, for example, to orient the working end 145 tocut targeted fibroid tissue. The tissue-cutting device 100 hassubsystems coupled to its handle 142 to enable electrosurgical cuttingof targeted tissue. A radio frequency generator or RF source 150 andcontroller 155 are coupled to at least one RF electrode carried by theworking end 145 as will be described in detail below. In one embodimentshown in FIG. 1, an electrical cable 156 and negative pressure source125 are operatively coupled to a connector 158 in handle 142. Theelectrical cable couples the RF source 150 to the electrosurgicalworking end 145. The negative pressure source 125 communicates with atissue-extraction channel 160 in the shaft assembly 140 of the tissueextraction device 100 (FIG. 4).

FIG. 1 further illustrates a seal housing 162 that carries a flexibleseal 164 carried by the hysteroscope handle 104 for sealing the shaft140 of the tissue-cutting device 100 in the working channel 102 toprevent distending fluid from escaping from a uterine cavity.

In one embodiment as shown in FIG. 1, the handle 142 of tissue-cuttingdevice 100 includes a motor drive 165 for reciprocating or otherwisemoving a cutting component of the electrosurgical working end 145 aswill be described below. The handle 142 optionally includes one or moreactuator buttons 166 for actuating the device. In another embodiment, afootswitch can be used to operate the device. In one embodiment, thesystem includes a switch or control mechanism to provide a plurality ofreciprocation speeds, for example 1 Hz, 2 Hz, 3 Hz, 4 Hz and up to 8 Hz.Further, the system can include a mechanism for moving and locking thereciprocating cutting sleeve in a non-extended position and in anextended position. Further, the system can include a mechanism foractuating a single reciprocating stroke.

Referring to FIGS. 1 and 4, an electrosurgical tissue-cutting device hasan elongate shaft assembly 140 extending about longitudinal axis 168comprising an exterior or first outer sleeve 170 with passageway orlumen 172 therein that accommodates a second or inner sleeve 175 thatcan reciprocate (and optionally rotate or oscillate) in lumen 172 to cuttissue as is known in that art of such tubular cutters. In oneembodiment, the tissue-receiving window 176 in the outer sleeve 170 hasan axial length ranging between 10 mm and 30 mm and extends in a radialangle about outer sleeve 170 from about 45° to 210° relative to axis 168of the sleeve. The outer and inner sleeves 170 and 175 can comprise athin-wall stainless steel material and function as opposing polarityelectrodes as will be described in detail below. FIGS. 6A-8 illustrateinsulative layers carried by the outer and inner sleeves 170 and 175 tolimits, control and/or prevent unwanted electrical current flows betweencertain portions go the sleeve. In one embodiment, a stainless steelouter sleeve 170 has an O.D. of 0.143″ with an I.D. of 0.133″ and withan inner insulative layer (described below) the sleeve has a nominalI.D. of 0.125″. In this embodiment, the stainless steel inner sleeve 175has an O.D. of 0.120″ with an I.D. of 0.112″. The inner sleeve 175 withan outer insulative layer has a nominal O.D. of about 0.123″ to 0.124″to reciprocate in lumen 172. In other embodiments, outer and or innersleeves can be fabricated of metal, plastic, ceramic of a combinationthereof. The cross-section of the sleeves can be round, oval or anyother suitable shape.

As can be seen in FIG. 4, the distal end 177 of inner sleeve 175comprises a first polarity electrode with distal cutting electrode edge180 about which plasma can be generated. The electrode edge 180 also canbe described as an active electrode during tissue cutting since theelectrode edge 180 then has a substantially smaller surface area thanthe opposing polarity or return electrode. In one embodiment in FIG. 4,the exposed surfaces of outer sleeve 170 comprises the second polarityelectrode 185, which thus can be described as the return electrode sinceduring use such an electrode surface has a substantially larger surfacearea compared to the functionally exposed surface area of the activeelectrode edge 180.

In one aspect of the invention, the inner sleeve or cutting sleeve 175has an interior tissue extraction lumen 160 with first and secondinterior diameters that are adapted to electrosurgically cut tissuevolumes rapidly—and thereafter consistently extract the cut tissuestrips through the highly elongated lumen 160 without clogging. Nowreferring to FIGS. 5 and 6A, it can be seen that the inner sleeve 175has a first diameter portion 190A that extends from the handle 142(FIG. 1) to a distal region 192 of the sleeve 175 wherein the tissueextraction lumen transitions to a smaller second diameter lumen 190Bwith a reduced diameter indicated at B which is defined by the electrodesleeve element 195 that provides cutting electrode edge 180. The axiallength C of the reduced cross-section lumen 190B can range from about 2mm to 20 mm. In one embodiment, the first diameter A is 0.112″ and thesecond reduced diameter B is 0.100″. As shown in FIG. 5, the innersleeve 175 can be an electrically conductive stainless steel and thereduced diameter electrode portion also can comprise a stainless steelelectrode sleeve element 195 that is welded in place by weld 196 (FIG.6A). In another alternative embodiment, the electrode and reduceddiameter electrode sleeve element 195 comprises a tungsten tube that canbe press fit into the distal end 198 of inner sleeve 175. FIGS. 5 and 6Afurther illustrates the interfacing insulation layers 202 and 204carried by the first and second sleeves 170, 175, respectively. In FIG.6A, the outer sleeve 170 is lined with a thin-wall insulative material200, such as PFA, or another material described below. Similarly, theinner sleeve 175 has an exterior insulative layer 202. These coatingmaterials can be lubricious as well as electrically insulative to reducefriction during reciprocation of the inner sleeve 175.

The insulative layers 200 and 202 described above can comprise alubricious, hydrophobic or hydrophilic polymeric material. For example,the material can comprise a bio-compatible material such as PFA,TEFLON®, polytetrafluroethylene (PTFE), FEP (Fluorinatedethylenepropylene), polyethylene, polyamide, ECTFE(Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride orsilicone.

Now turning to FIG. 6B, another variation of inner sleeve 175 isillustrated in a schematic view together with a tissue volume beingresected with the plasma electrode edge 180. In this embodiment, as inother embodiments in this disclosure, the RF source operates at selectedoperational parameters to create a plasma around the electrode edge 180of electrode sleeve 195 as is known in the art. Thus, the plasmagenerated at electrode edge 180 can cut and ablate a path P in thetissue 220, and is suited for cutting fibroid tissue and other abnormaluterine tissue. In FIG. 6B, the distal portion of the cutting sleeve 175includes a ceramic collar 222 which is adjacent the distal edge 180 ofthe electrode sleeve 195. The ceramic 222 collar functions to confineplasma formation about the distal electrode edge 180 and functionsfurther to prevent plasma from contacting and damaging the polymerinsulative layer 202 on the cutting sleeve 175 during operation. In oneaspect of the invention, the path P cut in the tissue 220 with theplasma at electrode edge 180 provides a path P having an ablated widthindicated at W, wherein such path width W is substantially wide due totissue vaporization. This removal and vaporization of tissue in path Pis substantially different than the effect of cutting similar tissuewith a sharp blade edge, as in various prior art devices. A sharp bladeedge can divide tissue (without cauterization) but applies mechanicalforce to the tissue and may prevent a large cross section slug of tissuefrom being cut. In contrast, the plasma at the electrode edge 180 canvaporize a path P in tissue without applying any substantial force onthe tissue to thus cut larger cross sections or slugs strips of tissue.Further, the plasma cutting effect reduces the cross section of tissuestrip 225 received in the tissue-extraction lumen 190B. FIG. 6B depictsa tissue strip to 225 entering lumen 190B which has such a smallercross-section than the lumen due to the vaporization of tissue. Further,the cross section of tissue 225 as it enters the larger cross-sectionlumen 190A results in even greater free space 196 around the tissuestrip 225. Thus, the resection of tissue with the plasma electrode edge180, together with the lumen transition from the smaller cross-section(190B) to the larger cross-section (190A) of the tissue-extraction lumen160 can significantly reduce or eliminate the potential for successiveresected tissue strips 225 to clog the lumen. Prior art resectiondevices with such small diameter tissue-extraction lumen typically haveproblems with tissue clogging.

In another aspect of the invention, the negative pressure source 225coupled to the proximal end of tissue-extraction lumen 160 (see FIGS. 1and 4) also assists in aspirating and moving tissue strips 225 in theproximal direction to a collection reservoir (not shown) outside thehandle 142 of the device.

FIGS. 7A-7B illustrate the change in lumen diameter of cutting sleeve175 of FIG. 6B. FIG. 8 illustrates the distal end of a variation ofcutting sleeve 175′ which is configured with an electrode cuttingelement 195′ that is partially tubular in contrast to the previouslydescribed tubular electrode element 195 (FIGS. 5 and 6A). FIGS. 9A-9Bagain illustrate the change in cross-section of the tissue-extractionlumen between reduced cross-section region 190B′ and the increasedcross-section region 190A′ of the cutting sleeve 175′ of FIG. 8. Thus,the functionality remains the same whether the cutting electrode element195′ is tubular or partly tubular. In FIG. 8A, the ceramic collar 222′is shown, in one variation, as extending only partially around sleeve175 to cooperate with the radial angle of cutting electrode element195′. Further, the variation of FIG. 8 illustrates that the ceramiccollar 222′ has a larger outside diameter than insulative layer 202.Thus, friction may be reduced since the short axial length of theceramic collar 222′ interfaces and slides against the interfacinginsulative layer 200 about the inner surface of lumen 172 of outersleeve 170.

In general, one aspect of the invention comprises a tissue cutting andextracting device (FIGS. 10A-11C) that includes first and secondconcentric sleeves having an axis and wherein the second (inner) sleeve175 has an axially-extending tissue-extraction lumen therein, andwherein the second sleeve 175 is moveable between axially non-extendedand extended positions relative to a tissue-receiving window 176 infirst sleeve 170 to resect tissue, and wherein the tissue extractionlumen 160 has first and second cross-sections. The second sleeve 175 hasa distal end configured as a plasma electrode edge 180 to resect tissuedisposed in tissue-receiving window 176 of the first sleeve 170.Further, the distal end of the second sleeve, and more particularly, theelectrode edge 180 is configured for plasma ablation of a substantiallywide path in the tissue. In general, the tissue-extraction device isconfigured with a tissue extraction lumen 160 having a distal endportion with a reduced cross-section that is smaller than across-section of medial and proximal portions of the lumen 160.

In one aspect of the invention, referring to FIGS. 7A-7B and 9A-9B, thetissue-extraction lumen 160 has a reduced cross-sectional area in lumenregion 190A proximate the plasma cutting tip or electrode edge 180wherein said reduced cross section is less that 95%, 90%, 85% or 80%than the cross sectional area of medial and proximal portions 190B ofthe tissue-extraction lumen, and wherein the axial length of thetissue-extraction lumen is at least 10 cm, 20 cm, 30 cm or 40 cm. In oneembodiment of tissue-cutting device 100 for hysteroscopic fibroidcutting and extraction (FIG. 1), the shaft assembly 140 of thetissue-cutting device is 35 cm in length.

FIGS. 10A-10C illustrate the working end 145 of the tissue-cuttingdevice 100 with the reciprocating cutting sleeve or inner sleeve 175 inthree different axial positions relative to the tissue receiving window176 in outer sleeve 170. In FIG. 10A, the cutting sleeve 175 is shown ina retracted or non-extended position in which the sleeve 175 is at itproximal limit of motion and is prepared to advance distally to anextended position to thereby electrosurgically cut tissue positioned inand/or suctioned into in window 176. FIG. 10B shows the cutting sleeve175 moved and advanced distally to a partially advanced or medialposition relative to tissue cutting window 176. FIG. 10C illustrates thecutting sleeve 175 fully advanced and extended to the distal limit ofits motion wherein the plasma cutting electrode 180 has extended pastthe distal end 226 of tissue-receiving window 176 at which moment theresected tissue strip 225 in excised from tissue volume 220 and capturedin reduced cross-sectional lumen region 190A.

Now referring to FIGS. 10A-10C and FIGS. 11A-11C, another aspect of theinvention comprises “tissue displacement” mechanisms provided bymultiple elements and processes to “displace” and move tissue strips 225in the proximal direction in lumen 160 of cutting sleeve 175 to thusensure that tissue does not clog the lumen of the inner sleeve 175. Ascan be seen in FIG. 10A and the enlarged views of FIGS. 11A-11C, onetissue displacement mechanism comprises a projecting element 230 thatextends proximally from distal tip 232 which is fixedly attached toouter sleeve 170. The projecting element 230 extends proximally alongcentral axis 168 in a distal chamber 240 defined by outer sleeve 170 anddistal tip 232. In one embodiment depicted in FIG. 11A, the shaft-likeprojecting element 230, in a first functional aspect, comprises amechanical pusher that functions to push a captured tissue strip 225proximally from the small cross-section lumen 190B of cutting sleeve 175as the cutting sleeve 175 moves to its fully advanced or extendedposition. In a second functional aspect, the chamber 240 in the distalend of sleeve 170 is configured to capture a volume of saline distendingfluid 244 from the working space, and wherein the existing RF electrodesof the working end 145 are further configured to explosively vaporizethe captured fluid 244 to generate proximally-directed forces on tissuestrips 225 resected and disposed in lumen 160 of the cutting sleeve 175.Both of these two functional elements and processes (tissue displacementmechanisms) can apply a substantial mechanical force on the capturedtissue strips 225 by means of the explosive vaporization of liquid inchamber 240 and can function to move tissue strips 225 in the proximaldirection in the tissue-extraction lumen 160. It has been found thatusing the combination of multiple functional elements and processes canvirtually eliminate the potential for tissue clogging the tissueextraction lumen 160.

More in particular, FIGS. 12A-12C illustrate sequentially the functionalaspects of the tissue displacement mechanisms and the explosivevaporization of fluid captured in chamber 240. In FIG. 12A, thereciprocating cutting sleeve 175 is shown in a medial position advancingdistally wherein plasma at the cutting electrode edge 180 is cutting atissue strip 225 that is disposed within lumen 160 of the cutting sleeve175. In FIG. 12A-12C, it can be seen that the system operates in firstand second electrosurgical modes corresponding to the reciprocation andaxial range of motion of cutting sleeve 175 relative to thetissue-receiving window 176. As used herein, the term “electrosurgicalmode” refers to which electrode of the two opposing polarity electrodesfunctions as an “active electrode” and which electrode functions as a“return electrode”. The terms “active electrode” and “return electrode”are used in accordance with convention in the art—wherein an activeelectrode has a smaller surface area than the return electrode whichthus focuses RF energy density about such an active electrode. In theworking end 145 of FIGS. 10A-11C, the cutting electrode element 195 andits cutting electrode edge 180 must comprise the active electrode tofocus energy about the electrode to generate the plasma for tissuecutting. Such a high-intensity, energetic plasma at the electrode edge180 is needed throughout stroke X indicated in FIG. 12A-12B to cuttissue. The first mode occurs over an axial length of travel of innercutting sleeve 175 as it crosses the tissue-receiving window 176, atwhich time the entire exterior surface of outer sleeve 170 comprises thereturn electrode indicated at 185. The electrical fields EF of the firstRF mode are indicated generally in FIG. 12A.

FIG. 12B illustrates the moment in time at which the distal advancementor extension of inner cutting sleeve 175 entirely crossed thetissue-receiving window 176. At this time, the electrode sleeve 195 andits electrode edge 180 are confined within the mostly insulated-wallchamber 240 defined by the outer sleeve 170 and distal tip 232. At thismoment, the system is configured to switch to the second RF mode inwhich the electric fields EF switch from those described previously inthe first RF mode. As can be seen in FIG. 12B, in this second mode, thelimited interior surface area 250 of distal tip 232 that interfaceschamber 240 functions as an active electrode and the distal end portionof cutting sleeve 175 exposed to chamber 240 acts as a return electrode.In this mode, very high energy densities occur about surface 250 andsuch a contained electric field EF can explosively and instantlyvaporize the fluid 244 captured in chamber 240. The expansion of watervapor can be dramatic and can thus apply tremendous mechanical forcesand fluid pressure on the tissue strip 225 to move the tissue strip inthe proximal direction in the tissue extraction lumen 160. FIG. 12Cillustrates such explosive or expansive vaporization of the distentionfluid 244 captured in chamber 240 and further shows the tissue strip 225being expelled in the proximal direction the lumen 160 of inner cuttingsleeve 175. FIG. 14 further shows the relative surface areas of theactive and return electrodes at the extended range of motion of thecutting sleeve 175, again illustrating that the surface area of thenon-insulated distal end surface 250 is small compared to surface 255 ofelectrode sleeve which comprises the return electrode.

Still referring to FIGS. 12A-12C, it has been found that a single powersetting on the RF source 150 and controller 155 can be configured both(i) to create plasma at the electrode cutting edge 180 of electrodesleeve 195 to cut tissue in the first mode, and (ii) to explosivelyvaporize the captured distention fluid 244 in the second mode. Further,it has been found that the system can function with RF mode-switchingautomatically at suitable reciprocation rates ranging from 0.5 cyclesper second to 8 or 10 cycles per second. In bench testing, it has beenfound that the tissue-cutting device described above can cut and extracttissue at the rate of from 4 grams/min to 8 grams/min without anypotential for tissue strips 225 clogging the tissue-extraction lumen160. In these embodiments, the negative pressure source 125 also iscoupled to the tissue-extraction lumen 160 to assist in applying forcesfor tissue extraction.

Of particular interest, the fluid-capture chamber 240 defined by sleeve170 and distal tip 232 can be designed to have a selected volume,exposed electrode surface area, length and geometry to optimize theapplication of expelling forces to resected tissue strips 225. In oneembodiment, the diameter of the chamber is 3.175 mm and the length is5.0 mm which taking into account the projecting element 230, provided acaptured fluid volume of approximately 0.040 mL. In other variations,the captured fluid volume can range from 0.004 to 0.080 mL.

In one example, a chamber 240 with a captured liquid volume of 0.040 mLtogether with 100% conversion efficiency in and instantaneousvaporization would require 103 Joules to heat the liquid from roomtemperature to water vapor. In operation, since a Joule is a W*s, andthe system reciprocate at 3 Hz, the power required would be on the orderof 311 W for full, instantaneous conversion to water vapor. Acorresponding theoretical expansion of 1700× would occur in the phasetransition, which would results in up to 25,000 psi instantaneously(14.7 psi×1700), although due to losses in efficiency andnon-instantaneous expansion, the actual pressures would be much less. Inany event, the pressures are substantial and can apply significantexpelling forces to the captured tissue strips 225.

Referring to FIG. 12A, the interior chamber 240 can have an axial lengthfrom about 0.5 mm to 10 mm to capture a liquid volume ranging from about0.004 mL 0.01 mL. It can be understood in FIG. 12A, that the interiorwall of chamber 240 has an insulator layer 200 which thus limits theelectrode surface area 250 exposed to chamber 240. In one embodiment,the distal tip 232 is stainless steel and is welded to outer sleeve 170.The post element 248 is welded to tip 232 or machined as a featurethereof. The projecting element 230 in this embodiment is anon-conductive ceramic. FIG. 13 shows the cross-section of the ceramicprojecting element 230 which is fluted, which in one embodiment hasthree flute elements 260 in three corresponding axial grooves 262 in itssurface. Any number of flutes, channels or the like is possible, forexample from 2 to about 20. The purpose of this design is to provide asignificant cross-sectional area at the proximal end of the projectingelement 230 to push the tissue strip 225, while at the same time thethree grooves 262 permit the proximally-directed jetting of water vaporto impact the tissue exposed to the grooves 262. In one embodiment, theaxial length D of the projecting element 230 is configured to pushtissue entirely out of the reduced cross-sectional region 190B of theelectrode sleeve element 195. In another embodiment, the volume of thechamber 240 is configured to capture liquid that when explosivelyvaporized provided a gas (water vapor) volume sufficient to expand intoand occupy at least the volume defined by a 10% of the total length ofextraction channel 160 in the device, at least 20% of the extractionchannel 160, at least 40% of the extraction channel 160, at least 60% ofthe extraction channel 160, at least 80% of the extraction channel 160or at least 100% of the extraction channel 160.

As can be understood from FIGS. 12A to 12C, the distending fluid 244 inthe working space replenishes the captured fluid in chamber 240 as thecutting sleeve 175 moves in the proximal direction or towards itsnon-extended position. Thus, when the cutting sleeve 175 again moves inthe distal direction to cut tissue, the interior chamber 240 is filledwith fluid 244 which is then again contained and is then available forexplosive vaporization as described above when the cutting sleeve 175closes the tissue-receiving window 176. In another embodiment, a one-wayvalve can be provided in the distal tip 232 to draw fluid directly intointerior chamber 240 without the need for fluid to migrate throughwindow 176.

FIG. 15 illustrates another variation in which the active electrodesurface area 250′ in the second mode comprises a projecting element 230with conductive regions and non-conductive regions 260 which can havethe effect of distributing the focused RF energy delivery over aplurality of discrete regions each in contact with the captured fluid244. This configuration can more efficiently vaporize the captured fluidvolume in chamber 240. In one embodiment, the conductive regions 250′can comprise metal discs or washers on post 248. In other variation (notshown) the conductive regions 250′ can comprise holes, ports or pores ina ceramic material 260 fixed over an electrically conductive post 248.

In another embodiment, the RF source 150 and controller 155 can beprogrammed to modulate energy delivery parameters during stroke X andstroke Y in FIGS. 12A-12C to provide the optimal energy (i) for plasmacutting with electrode edge 180, and (ii) for explosively vaporizing thecaptured fluid in chamber 240.

FIGS. 16A-16 and FIG. 17 illustrate another embodiment RF cutting probe400 that is similar to the above described embodiments. The variation ofFIGS. 16A-16C includes dielectric features and components in the workingend that permit optimal generation of plasma about the RF cuttingelectrode carried by the inner cutting sleeve.

FIGS. 16A-16B illustrate the working end of probe 400 and moreparticularly distal end 410 of the outer cutting sleeve 415 and thewindow 420 therein. This embodiment, in its final assembly shown in FIG.16B, provides a dielectric window edge 422 that comprises a dielectricmaterial of a similar thickness as the wall thickness of the outersleeve 415. This wall thickness can range from about 0.003″ to 0.010″.As can be seen in FIG. 16B, the window 420 in outer cutting sleeve 415is configured with a plurality of “key” features 425 that permit securecoupling of the dielectric edge 422 to the sleeve 415.

FIG. 16A illustrates the metal outer sleeve 415 as manufactured withoutintegration of the dielectric edge 422. It can be seen that a pluralityof keys 425 are machined into the metal window edge or interface 428,wherein the term keys is used to mean features that greatly increase thesurface area of the window edge perimeter or interface 428 thatinterfaces with a molded-in dielectric material 422. In one embodiment,the metal window edge 428 has cut features or keys 425 that have a widthWW ranging from 0.002″ to 0.020″ and a depth DD of 0.002″ to 0.020″. Inone aspect of the invention, the surface area of the edge interface 428is at least 200%, 300%, 400% or 500% greater than a window edge withoutsuch keys 425. In one variation in FIGS. 16A and 17, it can be seen thateach key 425 is configured with an increased cross section feature 433which will resist de-coupling forces in the rotational directionindicated arrow CC in FIG. 16A. In the enlarged view of FIG. 17, anothervariation includes radially slanted or beveled edges 440 on keys 425 tofurther resist de-coupling forces in an outward direction indicated atarrow DD.

Now turning to FIG. 16B, a method of making the distal end 410 can beunderstood. In a method of manufacturing, the dielectric polymermaterial 422 is molded in place as depicted in FIG. 16B by inserting acore pin in the lumen 435 the keyed outer sleeve 415 as shown in FIG.16A. The core pin matches the diameter of lumen 435 in the outer sleeve415. Thereafter, an outer mold component (not shown) is placed aroundthe exterior of outer sleeve 415 with the mold component matching theO.D. of the outer sleeve 415. Thereafter, a polymer can be injected intothe space between the core pin and outer mold which is equivalent to thesleeve wall in the space left by the window 420. In an injection moldingprocess, polymer can be injected to infill the keys 425 in the outersleeve 415 as well as the window 420. Thereafter, the final window 420can be cut out leaving the dielectric edge 422 having a suitable radialdimension RD around the window which can range from about 0.005″ to0.025″ as depicted in FIG. 16B. In one embodiment, the dielectricmaterial can be ABS, Nylon or polypropylene. In one variation, thedielectric material has a comparative tracking index value ranging from200 volts to 800 volts which helps to insure that the dielectricmaterial remains intact throughout a tissue cutting procedure. In othervariations, the dielectric material can comprise at least one of apolymer, ceramic, or glass.

It can be understood from FIG. 16A that the keys 425 of sleeve 415 willlock the dielectric edge 422 in place to prevent rotational or axialmovement of the dielectric edge 422 relative to the sleeve 415. Nowturning to FIG. 17, it should be appreciated keys 425 can be furthershaped to prevent radial outward displacement of the dielectric edge 422relative to the metal sleeve 415. In the enlarged view of FIG. 17, thisvariation includes radially slanted or beveled edges 440 on keys 425 tofurther resist de-coupling forces in an outward direction indicated atarrow DD.

FIG. 16C illustrates a final step in assembling an outer sleeve 415which comprises bonding a thin wall dielectric material or layer 442 inthe lumen 435 of the outer sleeve. This dielectric material 442 can beany suitable polymer, such as FEP, Teflon, etc., and can have athickness ranging from about 0.001″ to 0.010″ and functions to separatethe conductive inner sleeve 450 from the conductive outer sleeve 415which comprise opposing polarity electrodes as described in previousembodiments. FIG. 17 shows that the dielectric layer 442 overlaps and isbonded to the dielectric edge 422 shown in phantom view. The innerdielectric layer 442 lining the outer sleeve 415 has a further functionin that it provides a lubricious surface against which the inner sleeve450 can reciprocate. In another variation shown in FIG. 17, the innersleeve 450 can be fabricated with an outer polymer dielectric layer 452which serves a further electrical insulation and as a lubricious layerbetween the sleeves 415 and 450.

FIG. 16C further shows the inner cutting sleeve 450 in phantom viewdisposed within the lumen 435 of the outer sleeve 415 in itsreciprocating stroke. In one aspect of the invention, the dielectricedge 422 of the window 420 is configured to provide a predetermineddimensional range between the first polarity RF cutting electrode 460(see FIG. 17) and the exposed surface 465 of outer sleeve 415 whichcomprises the second polarity electrode. In FIG. 16C, the distal end 468of the inner cutting sleeve 450 is shown in phantom view in two axialpositions in the window 420. It should be appreciated that the stroke ofthe inner cutting sleeve 450 extends over the length of the window whichcan range from about 5 mm to 25 mm or more. The configuration thedielectric edge 422 and the dielectric layer 442 in that the firstpolarity electrode 460 carried by inner sleeve 450 and a second polarityelectrode 465 (comprising an exterior surface of outer sleeve 425) ismaintained in a very narrow dimensional range no matter the location ofinner sleeve 450 in its stroke. In one aspect the invention, the workingend assembly in configured to maintain spacing between the first andsecond polarity electrodes, or stated differently, to maintain thelength of the RF current path CP (see FIG. 17) throughout the strokebetween 0.015″ and 0.050″.

More specifically, referring to FIG. 17, the dimension of the currentpath CP between the RF cutting electrode 460 and the electrode surface465 of outer sleeve 415 about the window 420 is shown. In FIG. 17, itcan be seen that the cutting electrode 460, as described in previousembodiments, is stepped down in diameter from larger diameter portion470 of inner sleeve 450 that slidably contacts the lumen 435 in outersleeve 415. As described above in relation to FIGS. 8 and 9, the stepdown in diameter of the RF cutting electrode sleeve can range from0.010″ to 0.040″. Further, in the embodiment shown in FIG. 17, the innersleeve 450 is shown configured with optional dielectric exterior layer452 with a thickness of 0.001″ to 0.010″ that slidably cooperates withdielectric lining 442 of the outer sleeve. In FIG. 17, the shortestdimension of the current path CP between the opposing polarityelectrodes thus consists of current path portion radially outward fromthe RF electrode 460 over the dielectric edge 422 and thencircumferentially downward in current path portion to the metalelectrode 465 about the keys 425. It has been found by maintaining theprecise spacing between the opposing polarity electrodes throughout thestroke of the inner sleeve 450 can optimize plasma formation at thedistal edge of the RF cutting electrode 460 for cutting tissue.

In another aspect of the invention, referring to FIG. 17, the minimumcross-sectional area of the tissue-extracting channel in the innersleeve 450 is at least 40%, at least 45% or at least 50% of thecross-sectional area of outer sleeve 415. The relation between crosssections or components of the inner sleeve 450 and outer sleeve providesanother manner in which the spacing of opposing polarity electrodes canbe stated since each or the sleeves functions as a different polarityelectrode.

FIG. 18 illustrates another embodiment of outer sleeve 415′ in which thekeys take an alternative form. In FIG. 18, the keys comprise a pluralityof windows 470 through which polymer dielectric edge 422 can beinjection molded. Further, the wall of outer sleeve 415′ at the windowperimeter 472 can be reduced in cross-section from wall thickness T tolesser thickness T′. As can be understood from FIG. 18, the dielectricedge 422 when over-molded then can match the thickness of the wall ofouter sleeve 415′.

FIG. 19 illustrates another working end 480 that is similar to theembodiments described previously. In one variation, the exterior of theouter sleeve 485 is covered with a thin film dielectric material 488except for the electrode region indicated at 490. This embodimentfurther comprises slidable outer sleeve 495 of a substantially rigiddielectric material that can be moved over electrode 490. Thus, theexterior electrode 490 can be completely exposed, partly exposed orcompletely covered. In one aspect the invention, by covering theexterior electrode 490, the system can be made to operate only with anRF current path between the distal cutting electrode 460 and an internalelectrode surface of outer sleeve 485 as described in previousembodiments. In one variation, the inner cutting sleeve 495 may operateoptimally to more effectively achieve explosive vaporization of salinein the distal end chamber as the inner cutting sleeve 495 approaches thedistal end of its stroke, in performing the tissue-extraction functiondescribed in relation to FIGS. 12A-12C.

In another aspect of the invention, a method of cutting tissue comprisesproviding an elongated probe comprising a windowed outer sleeve and aninner sleeve that is reciprocatable to cut tissue in the window, whereina distal edge of the inner sleeve comprises a first polarity RF cuttingelectrode configured for plasma formation thereabout, manipulating thewindow into and out of contact with tissue in a saline environment whilereciprocating the inner sleeve and RF cutting electrode, and deliveringRF energy at system operational parameters such that a plasma is formedat the RF cutting electrode only when in contact with tissue. It hasbeen found that maintaining a fluid outflow cools the RF electrode andprevents vaporization and plasma formation. When the electrode contactstissue, the fluid flow about the electrode is impeded and plasmaignition occurs instantly. A negative pressure source as described abovecan provide a selected saline flow rate configured to prevent plasmaformation about the RF cutting electrode when not in contact withtissue.

While the above embodiments relate to reciprocating cutting sleeves, anelectrosurgical tissue cutting probe can also be configured with aninner cutting sleeve that moveable axially and/or rotationally to cuttissue.

It should be appreciated that while an RF source is suitable for causingexplosive vaporization of the captured fluid volume, any other energysource can be used and falls within the scope of the invention, such asan ultrasound transducer, HIFU, a laser or light energy source, amicrowave or a resistive heat source.

In another embodiment, the probe can be configured with a lumen incommunication with a remote liquid source to deliver fluid to theinterior chamber 240.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

What is claimed is:
 1. A method of resecting tissue with electrosurgicalenergy, comprising: inserting an elongated probe into a body cavity, theelongated probe comprising: a metallic outer sleeve having a windowextending through a side wall of the metallic outer sleeve at a locationbetween a proximal end and a distal end of the metallic outer sleeve,the metallic outer sleeve including a dielectric window edge engagedwith at least one interlocking feature formed in the side wall of themetallic outer sleeve; and an inner sleeve that is reciprocatable toresect tissue in the window, wherein a distal edge of the inner sleevecomprises a first polarity RF electrode configured for plasma formationthereabout; manipulating the window into and out of contact with tissuein a saline environment while reciprocating the inner sleeve and RFelectrode, and delivering RF energy to the RF electrode at systemoperational parameters such that a plasma is formed at the RF electrodeonly when in contact with tissue.
 2. The method of claim 1, whereindelivering RF energy causes current flow between the RF electrode and asurface of the outer sleeve comprising a second polarity electrode. 3.The method of claim 2, further comprising actuating a negative pressuresource in communication with a proximal end of a lumen in the innersleeve thereby causing a flow of saline through the lumen.
 4. The methodof claim 3, wherein the negative pressure source provides a selectedsaline flow rate configured to prevent plasma formation at the RFelectrode when not in contact with tissue.
 5. The method of claim 3,wherein positioning the RF electrode in contact with tissue restrictsthe saline flow rate resulting in plasma formation at the RF electrode.6. The method of claim 3, wherein positioning the RF electrode incontact with tissue increases impedance between the RF electrode and thesecond polarity electrode resulting in plasma formation at the RFelectrode.
 7. The method of claim 1, further comprising a dielectricmaterial extending around a perimeter of the window.
 8. The method ofclaim 7, wherein the dielectric material comprises polymer, ceramic, orglass.
 9. The method of claim 7, wherein delivering RF energy causescurrent flow across the dielectric material between the RF electrode anda surface of the outer sleeve comprising a second polarity electrode.10. The method of claim 1, wherein the first polarity RF electrode is aring electrode.
 11. A method of resecting tissue with electrosurgicalenergy, comprising: distending a body cavity with saline; inserting anelongated probe into the distended body cavity, the elongated probecomprising a metallic outer sleeve and an inner sleeve that is movablewithin the metallic outer sleeve, the metallic outer sleeve including atissue-receiving window having a plurality of keys formed in a side wallof the metallic outer sleeve and a dielectric window edge extending intothe plurality of keys to secure the dielectric window edge relative tothe outer sleeve, the inner sleeve including a first polarity RFelectrode movable across the tissue-receiving window to resect tissue inthe tissue-receiving window; manipulating the window into and out ofcontact with tissue in the distended body cavity while repeatedly movingthe first polarity RF electrode across the tissue-receiving window; anddelivering RF energy to the first polarity RF electrode at systemoperational parameters such that a plasma is formed at the RF electrodeonly when in contact with tissue.
 12. The method of claim 11, whereinthe first polarity RF electrode is configured for plasma formation at adistal edge thereof.
 13. The method of claim 11, wherein delivering RFenergy causes current flow between the RF electrode and a surface of theouter sleeve comprising a second polarity electrode.
 14. The method ofclaim 13, drawing a flow of the saline through a tissue extraction lumenof the inner sleeve to remove resected tissue from the body cavity. 15.The method of claim 14, controlling a flow rate of the saline throughthe tissue extraction lumen to prevent plasma formation at the RFelectrode when not in contact with tissue.
 16. The method of claim 15,wherein positioning the RF electrode in contact with tissue reduces theflow rate of the saline through the tissue extraction lumen resulting inplasma formation at the RF electrode.
 17. The method of claim 15,wherein positioning the RF electrode in contact with tissue increasesimpedance between the RF electrode and the second polarity electroderesulting in plasma formation about the RF electrode.
 18. The method ofclaim 11, further comprising a dielectric material extending around aperimeter of the tissue-receiving window.
 19. The method of claim 18,wherein delivering RF energy causes current flow across the dielectricmaterial between the RF electrode and a surface of the outer sleevecomprising a second polarity electrode.
 20. The method of claim 11,wherein the first polarity RF electrode is a ring electrode, and whereinthe plasma is formed at a distal edge thereof.